Name______Date______Period_____Scoreoutof25_____

The Effect of Exercise on Heart Rate

Howfastwillpulseincreasewithphysicalactivityandhowlongdoesittaketoreturntonormal?

Unlikemostworkers,theheartnevergetstimeoff.Eachhour,anaverageheartpumpsabout75gallonsofbloodthroughoutyourbody.Evenmoredifficult,duringexercisetheheartmustworkovertime.Theheartisthepumpthatcausesyourbloodtocirculatethroughoutyourbodyandtoallofyourcells.Theheartmakessurethattheoxygenyoubreathe,thenutrientsfromthefoodyoueat,andthewateryoudrink,getdeliveredtoyourbody. Withouttheheart,eachofyourorganswouldnotbeabletofunction.

Whenyouexercise,youincreasethedemandsforenergy.

Thereforeyourheartmustincreasethespeedatwhichtheblooddeliversthevitalnutrients.Butjusthowhardisyourheartwillingtowork? Inthisinvestigation,youwillexaminehowmuchyourheartratewillincreaseandtheamountoftimeittakesforyourhearttoreturntoitsnormalrate.

Materials

•ClockwithaSecondhand•Ruler

Settingup

Apulseisthevibrationscreatedeachtimeyourheartpumpsbloodthroughyourarteries.Therateofyourpulseindicatesthespeedofyourheartpumping.

Findalargetendonontheundersideofyourwrist.Usingyourmiddleandringfingerfromyourotherhand,locateyourpulsejustbelowthebaseofthethumbandontheoutsideofthelargetendon.

1.Feel the surface of your thumb. Whycan’tyouuseyourthumborindexfingertotakeyourpulse?

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  • Otherstudentstooktheirpulsetofindthenumberofbeatsperminute. TheyrecordedthisscorethreetimesinTable1andthenfoundtheaverage.
  • Studentsinthissamplehadanaveragerestingpulseraterangingfrom48to88.
Table1:Rateofpulsewhenresting
Name / RestingBeats/Minute
Trial1 / Trial2 / Trial3 / Average
Kevin / 48 / 47 / 49 / 49
Angelina / 60 / 59 / 61 / 60
Dana / 78 / 80 / 77 / 78
Yesenia / 90 / 85 / 88 / 88
Yourname

2.Nowit’syourturntofindyourrestingpulseratebeforeyouexercise. Astheteachertimesyoufor30seconds,countthebeatsinyourpulsethenmultiplythatnumberby2tofindthenumberofbeatsperminute.Repeatthesteptwomoretimes,andaverageyourresults.RecordyourresultsinTable1.

3.Thestudentsthenexercisedbydoingjumpingjacks. Theyhadpulseratesrangingfrom93to130beatsperminute. Whatdoyouthinkyourpulseratewillbeafteryoudo100jumpingjacks? Bespecific.______

Procedure

4.Do100jumpingjacks.Dothejumpingjacksinarowwithoutstopping.Afteryoustop,immediatelytakeyourpulsefor30seconds(x2).

a.Withoutexercisingagain,continuetotakeyoupulseforthenextfourminutes.Thiswilldeterminehowquicklyyourheartreturnstoitsrestingrate.RecordtheresultsaftereachminuteinTable2.

b.Otherstudents’pulseratesafterdoingjumpingjacksarealsolistedinTable2.

Results

Table2:Rateofpulseafterexercising

Name / Beats/Minute
immediately after
exercising / 1min.afterexercising / 2min.afterexercising / 3min.afterexercising / 4min.afterexercising
Kevin / 93 / 90 / 74 / 67 / 51
Angelina / 111 / 99 / 85 / 78 / 72
Dana / 120 / 109 / 90 / 70 / 60
Yesenia / 130 / 122 / 100 / 93 / 81
Yourname

SetuptheinformationfromTable2ontoGraph1(onthenextpage).

4. Writethetimevariableonthex-axis.Thisistheindependent(manipulated)variable. (2pts.)

5. Writethedependent(whatyouaremeasuring)variableonthey-axis.(2pts.)

6.Writethetitleintheformatofdependentvariablevs.independentvariable. Remembertowritewhatthesetermsactuallyareinyourtitle.(2pts.)

7.Youwillplaceyourdataandanotherstudent’sdatafromTable2onthesamegraph.Chooseonecolortorepresentyourpointsandanotherfortheotherstudent’spoints.Thenusetherulertocreatealineofbest-fit. Donottreatthepointsas“connect-the-dots.”Putyournameinparenthesisbyyourbest-fitlineandthestudent’snameinparenthesisbyhisorherbest-fitline.(4pts)

8.Extendthelinetoestimateyourheartrateaftertenminutesofresting.Usingthegraph,estimatehowlongitwouldtakeforthestudent’shearttoreturntoitsrestingrate.Therestingrateiscalculatedin

Table1. (2pts.)______

9.Whywoulditbeinaccuratetocontinuethegraphlineuntilithit0? (2pts.)

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10.Whatelse,besidesexercise,mightspeedupyourheartrate?Givetwoexamples.(2pts.)

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11.Whydoesyourheartrateincreasewhenyouexercise? What else changed? Your answer must show that you understand homeostasis.(5pts.)

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Name______Date______Period______

Graph1

Title

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